Well you didn't mention wheither or not it even blew cold air. First thing to do is check your fuses, if they are okay and If the fans not running check in the engine compartment under the battery and make sure there is a wire hooked up by the blower motor. Make sure there is water circulating to the heater box. If thats okay you can take out the 4 screws holding the heater controls in the dash and pull it out slightly and see if all your cables are still attached. If those things are okay then you need someone experienced with how the vacum is set up on the heater controls. Hope this helps, Steve

Mopar360yj
87yj+20,74CHR.030360,SOA,35BFGATs,46RH,241DHD,
D60-44-4.10

 

If the fan and everything is workiig ok then it is usually a sign that your water pump is going out.With the jeep running and hot grab the heater hose up by the firewall,if it is not hot the pump is starting to go bad.

Al
My web page

 

My 87yj's heater box had problems. It was not anything previously mentioned. The internal parts that direct the airflow had all fallen off and were blocking the airflow. I ended up taking the heater box out and doing a simple rebuild, if it could even be called that. When I put it back together I made sure to use lots of silicone selant on the seams. Then putting it back in was a PITA, but it works better than ever now that all of the cables work and actualy move something inside of the box.

Robert87yj

 

Or.................
If the Jeep is a resent acquisition, someone could have by passed the heater core when it went bad rather than replace it.

 

Could just be something as simple as the cable on the heater control slider came off, and when you slide the control level, you really aren't doing anything. Does it feel like there is resistance, and that you are really moving something when you slide the lever over to hot? Is the motor heating up on the temp gauge? If so, then I would say you either aren't moving the control (i.e., cable came disconnected under the dash or on the heater box) or the heater core was bypassed, as was mentioned.

Good luck,
Pete

88YJ,4"susp,33"BFGMTs,9000#winch, hm swing out TC/HL mount ,258,999,4.10,weber32/36,GMHEI.